/*
 *  SimpleImageInfo.java
 *
 *  @version 0.1
 *  @author  Jaimon Mathew <http://www.jaimon.co.uk>
 *
 *  A Java class to determine image width, height and MIME types for a number of image file formats without loading the whole image data.
 *
 *  Revision history
 *  0.1 - 29/Jan/2011 - Initial version created
 *
 *  -------------------------------------------------------------------------------
 
    This code is licensed under the Apache License, Version 2.0 (the "License"); 
    You may not use this file except in compliance with the License. 

    You may obtain a copy of the License at 

    http://www.apache.org/licenses/LICENSE-2.0 

    Unless required by applicable law or agreed to in writing, software 
    distributed under the License is distributed on an "AS IS" BASIS, 
    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
    See the License for the specific language governing permissions and 
    limitations under the License.
    
 *  -------------------------------------------------------------------------------
 */

package de.innovationgate.utils;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

/**
 * Bean class for quickly analyzing images for metadata
 */
@SuppressWarnings("all")
public class SimpleImageInfo {
    private int height;
    private int width;
    private String mimeType;

    private SimpleImageInfo() {

    }

    /**
     * Analyze an image file
     * @param file The file
     * @throws IOException
     */
    public SimpleImageInfo(File file) throws IOException {
        InputStream is = new FileInputStream(file);
        try {
            processStream(is);
        } finally {
            is.close();
        }
    }

    /**
     * Analyze image data on an input stream
     * @param is The stream
     * @throws IOException
     */
    public SimpleImageInfo(InputStream is) throws IOException {
        processStream(is);
    }

    /**
     * Analyze image data in a byte array
     * @param bytes The array
     * @throws IOException
     */
    public SimpleImageInfo(byte[] bytes) throws IOException {
        InputStream is = new ByteArrayInputStream(bytes);
        try {
            processStream(is);
        } finally {
            is.close();
        }
    }

    private void processStream(InputStream is) throws IOException {
        int c1 = is.read();
        int c2 = is.read();
        int c3 = is.read();

        mimeType = null;
        width = height = -1;

        if (c1 == 'G' && c2 == 'I' && c3 == 'F') { // GIF
            is.skip(3);
            width = readInt(is,2,false);
            height = readInt(is,2,false);
            mimeType = "image/gif";
        } else if (c1 == 0xFF && c2 == 0xD8) { // JPG
            while (c3 == 255) {
                int marker = is.read();
                int len = readInt(is,2,true);
                if (marker == 192 || marker == 193 || marker == 194) {
                    is.skip(1);
                    height = readInt(is,2,true);
                    width = readInt(is,2,true);
                    mimeType = "image/jpeg";
                    break;
                }
                is.skip(len - 2);
                c3 = is.read();
            }
        } else if (c1 == 137 && c2 == 80 && c3 == 78) { // PNG
            is.skip(15);
            width = readInt(is,2,true);
            is.skip(2);
            height = readInt(is,2,true);
            mimeType = "image/png";
        } else if (c1 == 66 && c2 == 77) { // BMP
            is.skip(15);
            width = readInt(is,2,false);
            is.skip(2);
            height = readInt(is,2,false);
            mimeType = "image/bmp";
        } 
        /*else { // Does not seem to work well: Wrong image sizes
            int c4 = is.read();
            if ((c1 == 'M' && c2 == 'M' && c3 == 0 && c4 == 42)
                    || (c1 == 'I' && c2 == 'I' && c3 == 42 && c4 == 0)) { //TIFF
                boolean bigEndian = c1 == 'M';
                int ifd = 0;
                int entries;
                ifd = readInt(is,4,bigEndian);
                is.skip(ifd - 8);
                entries = readInt(is,2,bigEndian);
                for (int i = 1; i <= entries; i++) {
                    int tag = readInt(is,2,bigEndian);
                    int fieldType = readInt(is,2,bigEndian);
                    long count = readInt(is,4,bigEndian);
                    int valOffset;
                    if ((fieldType == 3 || fieldType == 8)) {
                        valOffset = readInt(is,2,bigEndian);
                        is.skip(2);
                    } else {
                        valOffset = readInt(is,4,bigEndian);
                    }
                    if (tag == 256) {
                        width = valOffset;
                    } else if (tag == 257) {
                        height = valOffset;
                    }
                    if (width != -1 && height != -1) {
                        mimeType = "image/tiff";
                        break;
                    }
                }
            }
        }*/
        if (mimeType == null) {
            throw new IOException("Unsupported image type");
        }
    }
    
    private int readInt(InputStream is, int noOfBytes, boolean bigEndian) throws IOException {
        int ret = 0;
        int sv = bigEndian ? ((noOfBytes - 1) * 8) : 0;
        int cnt = bigEndian ? -8 : 8;
        for(int i=0;i<noOfBytes;i++) {
            ret |= is.read() << sv;
            sv += cnt;
        }
        return ret;
    }

    /**
     * Returns the height of the image in pixels
     */
    public int getHeight() {
        return height;
    }

    /**
     * Sets the height of the image in pixels
     */
    public void setHeight(int height) {
        this.height = height;
    }

    /**
     * Returns the width of the image in pixels
     */
    public int getWidth() {
        return width;
    }

    /**
     * Sets the width of the image in pixels
     */
    public void setWidth(int width) {
        this.width = width;
    }

    /**
     * Returns the images mime type
     */
    public String getMimeType() {
        return mimeType;
    }

    /**
     * Sets the images mime type
     */
    public void setMimeType(String mimeType) {
        this.mimeType = mimeType;
    }

    @Override
    public String toString() {
        return "MIME Type : " + mimeType + "\t Width : " + width + "\t Height : " + height; 
    }
}